The effect of dislocations on irradiation-induced vacancy-like defects in FeCu alloy and reactor pressure vessel steel

The effect of dislocations on irradiation-induced vacancy-like defects in FeCu alloy and RPV steel irradiated at room temperature by 3 MeV Fe ion at doses of 1 and 5 dpa was investigated by Doppler broadening spectroscopy (DBS), atom probe tomography (APT), and molecular dynamics (MD) simulations. We found that high-energy Fe-ion irradiation caused numerous large vacancy-like defects in FeCu alloy and RPV steel, resulting in an increase in S parameters and a decrease in W parameters. Note that Cu-vacancy complexes were detected in irradiated FeCu alloy, and high-density dislocations accelerate the formation of the Cu-vacancy complexes. However, higher dislocation density caused the decline of the S parameter and the increase of W parameter in both FeCu alloy and RPV steel. For the FeCu alloy, the change of S and W parameter is mainly due to the formation of Cu-vacancy complexes and sink effect of dislocations on point defects. For the RPV steel, only sink effect of dislocations on point effects suppress the formation and growth of vacancy-like defects, leading to the decline of S parameter and the increase of W parameter. The results of MD simulations confirmed that screw dislocations facilitate to promote the annihilation between interstitial- and vacancy-like defects produced by irradiation. (C) 2019 Elsevier B.V. All rights reserved.